The invention more specifically relates to multiple-disk brakes or to heat-sink type brakes, in opposition to rotary disk brakes in which the braking counterparts are constituted by sectors or pads covering only part of the surface of the rotary disk.
Multiple disk brakes generally comprise at least one rotor disk carried by a hub which is fast in rotation with the rotary shaft. Such brakes further comprise at least one static counterpart carrying at least one stator disk immobilized in an angular position in order to be placed in facing relationship to one of the faces of the rotor disk. And such brakes are also equipped with a system which controls the displacement of the stator disk, in parallel to the axis of the rotary shaft, toward the rotor disk on which it exerts a pressure with a view to braking its rotation.
Conventionally, a brake of the aforesaid type, comprises a rotor disk made entirely of metal, and equipped on either side with friction linings which are shaped as stator disk or disk-portions, produced in a material having a very good friction coefficient. Such a structure is found to be heavy and implies the use of relatively large unsuspended masses. In an attempt to overcome this drawback, it has been proposed, particularly in French Patent No. 2 557 240 (83-20 496), to produce the rotor disk by using a metallic core and applying on its two faces friction linings in a material having a good friction coefficient, such as for example, carbon-carbon, similarly to the stator disk or disks.
A brake of the above type is generally capable of much higher performances than a brake having a rotor disk in metal. Nevertheless, such a brake has been found to be limited, regarding energy dissipation, because of the structure of the rotor disk.
Indeed, because of the very nature of the metallic core, the rise in temperature during braking is limited. This limit is estimated to around 500.degree. C. The added friction linings, on the other hand, and particularly those in carbon-carbon, show good efficiency at higher temperatures, i.e. around 1300.degree. C.
The limit of absorption and dissipation is therefore conditional upon the performances of the metallic core, whereas the added friction linings have unquestionably higher capacities.
In those cases where the energies to be absorbed are especially high, it is necessary to adapt on the same rotary shaft, several brakes of similar type, in order to obtain that the energy to be dissipated be distributed on each one.
This necessity results in a considerably heavier, bulkier and more expensive assembly than the one only using one disk brake.
It might be assumed that the aforesaid problem could be solved by the fact of producing the rotor disks and the stator disks as described for example in patent application EP-A-0 171 164 and in a material having a good friction coefficient such as carbon-carbon. This solution might present certain advantages in applications where the rotary shafts are dismountable. But it has proved impracticable in those cases where the rotary shafts, on the contrary, form part of heavy, complex and undismountable structures which, on the other hand, are those with the highest levels of energy to be dissipated. This is for example the case of heavy vehicles, such as land or railway vehicles, transporting heavy loads and travelling at relatively high speeds.
In those cases, the use of rotors and stators shaped as annular disks and made of, for example, carbon-carbon, is unthinkable, because such disks cannot be readily mounted and dismounted everytime they need to be replaced.
It has been the object of prior art documents such as French patents FR-A-1 189 381 and 2 359 321 (77-22 829) to overcome the above-described problems by proposing a rotor and/or stator disk constituted of a plurality of sectors interconnected by way of bolts. This particular structure, however, is impossible, when using thermostructural friction materials, because of the different thermal resistance characteristics existing between the material constituting the friction parts and the material constituting the connecting parts.